JPH07311478A - Production of toner for developing electrostatic charge image - Google Patents

Abstract

PURPOSE:To produce a toner hardly causing image defects such as black spots, ensuring stable image and image quality characteristics even at the time of continuous use and excellent in durability and fixability. CONSTITUTION:An additive is added to toner particles each consisting of at least resin and a colorant at an addition temp. below the glass transition temp. of the resin and the result.ant toner is screened with a screening device fitted with a screen having <=200mum opening to produce the objective toner for developing an electrostatic charge image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of producing an electrostatic charge image developing toner used in electrophotography, electrostatic recording and the like.

[0002]

2. Description of the Related Art A developer used in an electronic copying machine or the like is once attached to an image carrier such as a photoconductor on which an electrostatic charge image is formed in the developing process, and then is transferred to the photoconductor in the transferring process. After being transferred from the sheet to the transfer sheet, it is fixed on the copy sheet surface in the fixing step. At that time, as a developer for developing the electrostatic charge image formed on the latent image holding surface, a two-component developer consisting of a carrier and a toner and a one-component developer not requiring a carrier (magnetic toner, non-magnetic toner). )It has been known.

Toners contained in the developer include positively chargeable toners and negatively chargeable toners. Conventionally, as those imparting chargeability to the positively chargeable toners, nigrosine dyes and quaternary ammonium salts are used. Further, as a material for imparting chargeability to a negatively chargeable toner, a charge control agent such as a metal-containing dye or a coating agent for imparting a predetermined chargeability to a carrier has been known. An example of a toner manufacturing flow that is normally performed is shown in FIG. First, a predetermined amount of materials such as a resin and a colorant are mixed and mixed, melt-kneaded with a kneader, cooled, pulverized, and classified. Further, after the classified toner and the external additive are stirred and mixed, foreign substances are sieved and filled in a container.

In recent years, as the speed of copying machines and the like has increased, the life of developers has increased (higher printing durability), and higher image quality has been achieved, the binder resin used for toner also has lower energy during fixing (lower temperature fixing). ), Higher mechanical strength, higher functionality such as ensuring storage stability, and higher performance are required. Therefore, the flow softening temperature of the binder resin tends to be designed to be lower than that of the fixing surface, and the toner particle diameter tends to be reduced in order to achieve high image quality. Furthermore, improvement of fluidity of toner,
For the purpose of improving storage stability and charging characteristics, a means for stirring and mixing toner and various inorganic or organic external additives finer than the toner with a high-speed stirrer or the like has been taken.

However, in the external addition step of stirring and mixing the toner particles using a relatively soft resin and the external additive, heat is generated by high-speed stirring, agglomeration of the toner particles due to collision of the particles, toner and the external additive. Aggregation of the toner and the aggregation of the external additives generate an aggregate of the toner. When a printed matter such as a copy is taken using the toner containing the aggregate, several hundred μm to several m are present in the black portion or halftone portion of the copy.
There was a problem in that an image loss called "black core" caused by flying toner aggregates of about m occurred.

Conventionally, sieving with a sieving device such as a Sato type vibrating screen and a gyro shifter has been mentioned as a means for removing foreign substances in the toner, but the opening of the screen attached to the sieving device is mainly for removing foreign substances. Since it was intended, a relatively rough one, for example, one having a thickness of 300 to 400 μm was used. Such a coarse screen screen sieving device cannot sufficiently reduce the agglomerates in the externally added toner and cannot completely eliminate the image loss such as the black core on the copy. .

[0007]

Therefore, the first aspect of the present invention
It is an object of the present invention to provide a toner having less image loss such as "black core" on printed matter such as copy and excellent in image characteristics such as image density and fog. The second purpose is excellent fixing properties,
Another object of the present invention is to provide a toner having excellent storage stability during storage at high temperatures. A third object is to provide a toner that has stable image characteristics, image quality, charging characteristics, and the like, and has excellent durability even after continuous copying.

[0008]

As a result of various studies made by the present inventors, it has been found that the toner performance can be improved by externally adding an external additive to the toner by a specific method and then sieving with a sieving device. Found and arrived at the present invention. That is, the gist of the present invention is to externally add an external additive to toner particles composed of at least a resin and a colorant under the condition of the glass transition temperature of the resin or less, and then open the externally added toner to 200 μm.
A method for producing a toner for developing an electrostatic charge image, which comprises obtaining a toner through a step of sieving with a sieving apparatus having a screen of m or less. Hereinafter, the present invention will be described in detail.

As the resin used in the present invention, known types suitable for toner can be used. For example, polystyrene, chloropolystyrene, poly-α-methylstyrene,
Styrene-chlorostyrene copolymer, styrene-propylene copolymer, styrene-butadiene copolymer, styrene-vinyl chloride copolymer, styrene-vinyl acetate copolymer, styrene-acrylic acid ester copolymer (styrene-acrylic Methyl acid copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer,
Styrene-octyl acrylate copolymer and styrene-
Phenyl acrylate copolymer, etc.), styrene-methacrylic acid ester copolymer (styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer and styrene-phenyl methacrylate) Copolymers, etc.), styrene-α-chloromethyl acrylate copolymers and styrene-acrylonitrile-acrylic acid ester copolymers and other styrenic resins (styrene or styrene-substituted homopolymers or copolymers), Vinyl chloride resin, rosin-modified maleic acid resin, phenol resin, epoxy resin, polyester resin, polyethylene resin, polypropylene resin, ionomer resin, polyurethane resin, silicone resin, ketone resin, ethylene-ethyl acrylate copolymer, xylene resin, polyvinyl Butyral resins, as well as polycarbonate resin, etc. However, particularly preferred resins for use in the present invention may be a styrene resin, saturated or unsaturated polyester resin and epoxy resin are exemplified.
Further, the above resins are not limited to be used alone, but may be used in combination of two or more kinds.

The flow softening temperature (Tm) of the resin is 8
The temperature is preferably about 0 to 150 ° C, more preferably about 90 to 140 ° C. If the temperature is lower than 80 ° C, the fixing temperature on the paper is low and good, but hot offset is likely to occur, and the toner is easily crushed inside the developing tank, resulting in a spent phenomenon in which the toner adheres to the carrier surface and the doctor blade. However, there is a problem in that the charging characteristics are deteriorated and the durability performance of the developer is deteriorated. On the other hand, if it is higher than 150 ° C., the fixing temperature on the fixing paper is high, and the toner pulverizability is poor.

The glass transition temperature of the resin is preferably about 50 ° C. or higher, and when the temperature is lower than 50 ° C., the toner is hard to agglomerate or stick when left at a high temperature of 40 ° C. for a long time, resulting in poor storage stability. There is a problem in use such that toner agglomerates are likely to be generated in the external addition step, and that they are easily attached to the screen of the sieving device and the rotating rotor to generate agglomerates. The flow softening temperature (Tm) and glass transition temperature (Tg) of the resin are measured as follows.

[Flow Softening Temperature (Tm)] In a flow tester (CFT-500 manufactured by Shimadzu Corporation),
Sample 1g, nozzle 1mm × 10mm die, load 30k
g, a preheating time of 50 ° C. for 5 minutes, and a temperature rise rate of 3 ° C./min. The measurement is performed. [Glass transition temperature (Tg)] In a differential thermal analyzer (DTA-40 manufactured by Shimadzu Corporation), a temperature rising rate of 10 ° C /
A tangent line is drawn at the transition (inflection) start portion of the curve measured under the condition of minutes, and the intersection temperature is taken as the glass transition temperature.

As the colorant used in the present invention, known pigments and dyes may be used. For example, carbon black,
Titanium oxide, zinc white, alumina white, calcium carbonate, ultramarine blue, navy blue, phthalocyanine blue, phthalocyanine green, Hansa yellow G, rhodamine dye, chrome yellow, quinacridone, benzidine yellow, rose bengal, triallyl methane dye, anthraquinone dye, Colorants such as monoazo and disazo dyes and pigments may be used alone or in combination of two or more. The content of the colorant may be an amount sufficient to color the toner so that a visible image can be formed by development, and for example, resin 10
1 to 20 parts by weight based on 0 parts by weight, and particularly 3 to 15 parts by weight
Weight parts are preferred.

Further, known positively-charged or negatively-charged charge control agents may be used alone or in combination in the toner, and the amount thereof may be selected according to the desired charge amount ratio, for example, resin 100. About 0.05 to 10 parts by weight is preferable with respect to parts by weight. Examples of positively chargeable charge control agents include nigrosine dyes, quaternary ammonium salt compounds,
Triphenylmethane compounds, imidazole compounds,
Examples include polyamine resins. As the negative charge control agent, a metal-containing azo dye such as Cr, Co, Al, or Fe,
Examples thereof include metal salicylate compounds, metal alkylsalicylate compounds, and carlix arene compounds. Furthermore, if necessary, other internal additives may be used alone or in combination as an auxiliary agent, and examples thereof include a low molecular weight olefin polymer of a known release agent and a filler. First, an example of the toner manufacturing method of the present invention will be described with reference to FIG. 1, but the present invention is not limited to the following description as long as the gist thereof is not exceeded. As the toner internal additive, at least a predetermined amount of resin and colorant are weighed and mixed, and mixed.
Examples of the mixing device include a double-con mixer, a V-type mixer, a drum-type mixer, a super mixer, a Henschel mixer, and a Nauta mixer.

Next, in the kneading step, a batch type (for example,
A pressure kneader, a Banbury mixer, etc.) or a continuous kneader is used, but in recent years, single-screw or twin-screw extruders have become mainstream because of their superiority in continuous production. For example, KTK manufactured by Kobe Steel Ltd. Type twin-screw extruder, TEM type twin-screw extruder manufactured by Toshiba Machine Co., Ltd., twin-screw extruder manufactured by K.K.K., PCM type twin-screw extruder manufactured by Ikegai Tekko KK, Co-kneader manufactured by Bus Co., etc. Used for. After the kneading, the toner is rolled by a two-roll roll or the like, and goes through a cooling step of cooling with water or the like.

Next, in the pulverizing step, coarse pulverization is carried out with a crusher, hammer mill, feather mill or the like, and fine pulverization is carried out with a jet mill, a high speed rotor rotary mill or the like, and usually a predetermined toner particle size is provided in two or more stages. Crush up to.
After the pulverization, the toner is classified by an inertia classification type elbow jet, a centrifugal force classification type microplex, a DS separator and the like to obtain a toner having an average particle diameter of 3 to 15 μm. The toner coarse powder generated in the classification step may be returned to the crushing step, and the fine powder generated may be returned to the blending step of the toner raw materials for reuse.

Further, when the toner is externally added, a classified toner and various known external additives are mixed in a predetermined amount, and a high-speed stirrer such as a Henschel mixer or a super mixer which gives a shearing force to the powder is used. It is better to stir and mix. At this time, since heat is generated inside the external additive machine and aggregates are easily generated, it is preferable to adjust the temperature by means such as cooling the periphery of the container part of the external additive machine with water. The internal material temperature should be below the glass transition temperature of the resin,
A lower control temperature of about 10 ° C. or higher, especially a lower control temperature of 15 ° C. or higher is preferable. In practice, the material temperature may be regarded as the temperature inside the tank of the external addition machine. As the external additive, various known inorganic or organic external additives can be used,
In particular, fine inorganic powders of titania, silica, alumina, zinc oxide, magnesium oxide and the like are preferable in order to improve the fluidity of the toner and suppress the aggregation.

In order to improve the fluidity of the toner, the BET specific surface area of the external additive is 20 to 700 m ² / g, preferably 5
About 0 to 500 m ² / g is preferable. Specific surface area of 20m ² /
If it is less than g, sufficient fluidity cannot be imparted to the toner, the screen passing property in the sieving device is deteriorated, the toner yield is deteriorated (productivity is deteriorated), the transportability during development is deteriorated, and the triboelectric charging function is deteriorated. There is a beckoning problem. Also, the specific surface area is 700 m ² / g
If it is larger, the partition effect between the toner particles is lost, the storage stability at high temperature is deteriorated, and the external additives are easily aggregated, making it difficult to handle and uniformly disperse them on the toner surface.

The mixing amount of the external additive varies depending on the external additive to be used and the average particle size and particle size distribution of the toner particles, but the desired amount of toner fluidity is obtained, for example, with respect to 100 parts by weight of the toner particles. 0.05 to 10 parts by weight, and more preferably 0.1 to 8 parts by weight. If the mixing amount is less than 0.05 parts by weight, there is no fluidity improving effect and the yield in the sieving device is deteriorated. If the mixing amount is more than 10 parts by weight, filming is performed on the photoreceptor by the external additive that is partly released. It is not preferable because it may be generated or accumulated in the developing tank to cause troubles such as deterioration of the charging function of the developer.

From the viewpoint of stability in a high humidity environment, the external additive is more preferably an inorganic fine powder which has been subjected to a hydrophobic treatment with a treatment agent such as a known silane coupling agent, and is further charged. When considering the properties, dimethyldichlorosilane, monooctyltrichlorosilane, hexamethyldisilazane, silicone oil, etc. can be used as the treatment agent that imparts negative charge, and aminosilane, etc. can be used as the treatment agent that imparts positive chargeability. Good.

In addition, as a toner external additive, for the purpose of resistance adjustment, abrasives, etc., known magnetites other than those for improving fluidity, farite, conductive titanium, antimony oxide, tin oxide, cerium oxide, hydrotalcites, etc. An appropriate amount of fine powder such as a compound, acrylic beads, silicone beads, and polyethylene beads may be mixed, and the mixing amount is preferably 0.005 to 10 parts by weight with respect to 100 parts by weight of the toner. The BET specific surface area can be measured by using a commercially available nitrogen-adsorbing BET specific surface area measuring apparatus, for example, a flow type specific surface area automatic measuring apparatus (flow soap 2300 type) manufactured by Shimadzu Corporation. .

The externally added toner (hereinafter, referred to as externally added toner) is a known sieving device such as a Sato type vibrating screen, a gyro shifter, a centrifugal screen classifier, etc. to remove foreign matters, toner aggregates and the like. . In particular, in order to remove agglomerates in the toner generated in the external addition step, the screen opening of the sieving device is 200 μm or less, preferably 150 μm or less, which reduces the frequency of occurrence of black cores on the copy. be able to. It should be noted that the present invention works more effectively when a fine opening is used, but the toner yield (productivity) in the sieving step
In consideration of the above, it is possible to select the optimum screen opening timely depending on the device used, the amount of toner to be processed, and the like. In addition, it is preferable to use a conductive material for the screen, the mold, the powder passage, etc. of the sieving device and ground each to prevent electrostatic adhesion. Finally, the screened toner is filled in a container such as a bottle or a cartridge. The obtained toner is a one-component developer that does not use a carrier (a magnetic one-component toner containing a magnetic substance such as magnetite or a non-magnetic one-component toner containing no magnetic substance), or iron powder, ferrite, or magnetite. , A two-component developer mixed with a magnetic carrier such as a magnetic resin carrier.

[0023]

EXAMPLES In the following examples, "parts" simply means "parts by weight". <Example 1>

[0024]

[Table 1] Styrene / n-butyl acrylate = copolymer resin having a monomer weight ratio of 82/18 [Tm = 135 ° C., Tg = 64 ° C.] 100 parts Colorant Carbon Black MA-100 (Mitsubishi Kasei Co., Ltd.) ) 7 parts-Charge control agent Bontron P51 (Orient Chemical Co., Ltd.) 2 parts-Low molecular weight polypropylene 550P (Sanyo Kasei Co., Ltd.) 2 parts

Are mixed and mixed by a V-type mixer, and continuously 2
Kneading using a shaft extruder, cooling, jet mill grinding,
By air classification, a black toner having an average particle diameter of 10.5 μm was obtained. To 100 parts of this black toner, 0.2 part of silica powder (R972 of Nippon Aerosil Co., Ltd.) and 0.3 part of magnetite fine particles (EPT1000 of Toda Kogyo Co., Ltd.) were added to a super mixer (Kawata Seisakusho Model SMV-). 20)
Externally added at a tank temperature of 38 ° C., and then sieved with a gyro shifter equipped with a SUS screen having a screen opening of 149 μm to obtain a toner A. 4 parts of the obtained toner A and 100 parts of a ferrite powder carrier having an average particle diameter of 100 μm and surface-coated with a methylsilicone-containing resin were mixed and stirred to prepare a developer. Next, with respect to this developer, using a copier having a negatively chargeable organic photoconductor as a photoreceptor and a cleaning device provided with a blade made of urethane material, a copying machine having a copying speed of 35 sheets / min was used. A live-action test was conducted. Toner A was used as the replenishment toner. The results are shown in Table 1, and it was a developer and a toner which showed almost no black core on the copy after 50,000 sheets and had excellent image characteristics / quality and durability.

<Embodiment 2> Toner B was prepared by changing only the screen opening of the gyro shifter of Embodiment 1 to 105 μm.
Table 1 shows the results obtained by carrying out the same live-shooting test as in Example 1.
However, it was good.

Comparative Example 1 Toner C was prepared by changing the screen opening of the gyro shifter of Example 1 to 350 μm.
Table 1 shows the results obtained by carrying out the same live-shooting test as in Example 1.
However, many black cores were generated on the copy. <Example 3>

[0028]

[Table 2] Styrene / n-butyl acrylate = copolymer resin with a monomer weight ratio of 85/15 [Tm = 125 ° C., Tg = 59 ° C.] 100 parts Colorant Carbon Black MA-100 (Mitsubishi Kasei Co., Ltd.) ) 7 parts-Charge control agent Bontron P51 (Orient Chemical Co., Ltd.) 2 parts-Low molecular weight polypropylene 550P (Sanyo Kasei Co., Ltd.) 2 parts

Are mixed and mixed with a V-type mixer, and continuously 2
Kneading using a shaft extruder, cooling, jet mill grinding,
By air classification, a black toner having an average particle diameter of 8.5 μm was obtained. To 100 parts of this black toner, 0.35 part of silica powder (R972 of Nippon Aerosil Co., Ltd.) and 0.3 part of magnetite fine particles (EPT1000 of Toda Kogyo Co., Ltd.) were added to a super mixer (Kawata Seisakusho Model SMV-). Two
0) externally added at a bath temperature of 35 ° C., and sieved by a gyro shifter equipped with a SUS screen having a screen opening of 105 μm to obtain a toner D. Obtained Toner D
4 parts and 100 parts of a ferrite powder carrier having an average particle diameter of 100 μm and surface-coated with a methylsilicone-containing resin were mixed and stirred to prepare a developer. Next, with respect to this developer, using a copier having a negatively charged organic photoconductor as a photoreceptor and a cleaning device provided with a blade made of urethane material, a copying machine having a copying speed of 60 sheets / min was used to print 50,000 sheets. A live-action test was conducted. The results are shown in Table 1.
There is almost no black core on the copy through 00 sheets,
It was a developer and toner with excellent image characteristics / quality and durability.

<Embodiment 4> The screening apparatus of Embodiment 3 is equipped with a turbo screener (Turbo Kogyo Co., Ltd., model T) equipped with a polyester screen in which carbon fibers are woven from a gyro shifter and having a screen opening of 105 μm.
Toner E was obtained by changing to S250), and the same test as in Example 3 was performed. The results are shown in Table 1.

<Embodiment 5> Toner F was obtained by changing only the screen openings of the sieving apparatus of Embodiment 4 to 74 μm, and the result of the same actual copying test as in Embodiment 3 is shown in Table 1.
It was good.

Comparative Example 2 An actual copying test was conducted in the same manner as in Example 3 except that the toner G was obtained by changing only the screen openings of the sieving apparatus of Example 3 to 250 μm, and the results are shown in Table 1.
However, many black cores were generated on the copy.

<Example 6> Toner H was obtained by changing only the toner externally added formulation of Example 3 as follows. Silica powder for 100 parts of black toner (Japan Aerosil R972)
0.25 parts and magnetite fine particles (E, Toda Kogyo Co., Ltd.)
0.3 part of PT1000) was externally added to a super mixer (Kawata Seisakusho model SMV-20) at a tank temperature of 36 ° C. This externally added toner was subjected to an actual copying test in the same manner as in Example 3, and the results are shown in Table 1 and were almost good.

<Example 7> Toner I was obtained by changing only the external additive formulation of Example 3 as follows. Silica powder for 100 parts of black toner (Japan Aerosil R972)
0.4 parts and magnetite fine particles (Toda Kogyo EP
T1000) 0.3 part with a super mixer (Kawata Seisakusho model SMV-20) rotation speed 2,000 rpm
It was added externally for 3 minutes. This externally added toner was subjected to an actual copying test in the same manner as in Example 3, and the results are shown in Table 1 and were good.

[0035]

[Table 3]

[0036]

EFFECTS OF THE INVENTION By using the method for producing a toner for developing an electrostatic charge image of the present invention, the occurrence of image defects such as the black core of the toner is small, and the image and image quality characteristics are stable even during continuous use, and the durability is improved. It provides enormous industrial benefits such as providing toner performance with excellent performance and fixing performance.

[Brief description of drawings]

FIG. 1 is a manufacturing flow showing an example of a toner manufacturing method.

Claims (3)

[Claims] 1. A step of externally adding an external additive to toner particles composed of at least a resin and a colorant under a condition of a glass transition temperature of the resin or lower, and then the externally added toner is opened 20
A method for producing a toner for developing an electrostatic charge image, which comprises obtaining a toner through a step of sieving with a sieving apparatus equipped with a screen of 0 μm or less. 2. The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein the material temperature in the external addition step is lower than the glass transition temperature of the resin in the toner by 10 ° C. or more. 3. The screen opening of the sieving device has an opening of 150.
3. The method for producing a toner for developing an electrostatic charge image according to claim 1, wherein the toner has a thickness of not more than μm.